Scientists

Question 1

Olaus Römer

Answer 1

Used a bigger distance and determined light is not an infinite speed because it took a shorter amount of time when earth was moving toward Jupiter and longer away. He found the time it takes light to cross earth’s orbit to be roughly 22mins

Question 2

Christian hüygens

Answer 2

Measured the diameter of earths orbit to be 3.00x10^11m
Therefore c=d/t
C=2.27x10^8m/s

Question 3

Fizeau

Answer 3

Used a more accurate time measurement. Used a slotted disk (toothed wheel)
C=2d/time for 1 full rotation

Question 4

Albert Michaelson

Answer 4

Used accurate time measurement
Rotating 8 sided mirror (mirror must make exactly 1/8 of a rev. in the same it takes light to go from rotating to fixed mirror and back)

Question 5

James Clark Maxwell

Answer 5

Solely used mathematics to prove a theory however there was no evidence to support it. Used previous discoveries to derive a purely mathematical description of something he called EMR

Question 6

2 main ideas of Maxwell

Answer 6

1) A delta Ē produces B (magnetic field)

2) A delta B produces Ē

Question 7

Source of EMR is what?

Answer 7

Accelerated charge

Question 8

Maxwells predictions

Answer 8

• speed of EMR
• EMR should exert pressure
• frequency of EMR=frequency of oscillation of the charge
• share wave properties: interference, diffraction, reflection, refraction, etc

Question 9

Heinrich hertz

Answer 9

Used an induction coil and spark gap (the B of the EMR should induce an I (current) in the loop)

Question 10

Galileo

Answer 10

Tried to use v=d/t but light is too fast

Question 11

Snell

Answer 11

Created the snell law sin1/sin2=v1/v2=wavelength1/wavelength2=n2/n1

Question 12

Thomas young

Answer 12

Proved that light is a wave (used diffraction and interference) using a screen along with slits (wavelength=dsin/n)

Question 13

Poisson

Answer 13

Came up with the idea that if light is a wave, diffraction and constructive inference should produce a spot of light in the centre of a shadow. This does not happen therefore light is a particle

Question 14

Who proved poisson’s theory?

Answer 14

Dominique Arago found the spot therefore light is a wave

Question 15

Hüygens principle (wave)

Answer 15

Every point on a wavefront behaves like a point source of circular wavefronts that are in phase–to produce a new wavefront (tangent)

Question 16

Max Planck

Answer 16

Black body radiation
Thought maybe EMR didn’t exist as a continuous wave, but as tiny individual chunks called quanta
E=hf
H=plancks constant

Question 17

Einstein

Answer 17

Maybe EMR is not a continuous wave but photons

Question 18

Einstein’s main ideas

Answer 18

• an election can absorb one and only one photon at a time
• if f is bigger than fo a single photon can give the electron enough energy to leave the surface
• if f is smaller than fo, a single photon does not have enough energy to leave the surface

Question 19

Arthur Compton

Answer 19

Used the scattering of low energy xrays end electrons from a thin metal foil which has been struck with higher energy xrays

Question 20

De Broglie

Answer 20

Found wavelength=h/mv

Question 21

GP Thomson

Answer 21

Proved that electrons have wave properties
Diffracts: don’t see them
Reflects: see them
Smaller wavelength=more particle less wave property
Mid wavelength=more wave property